The present-day chemical composition of the LMC

Rolleston, W. R. J.; Trundle, C.; Dufton, P. L.

doi:10.1051/0004-6361:20021088

Cited by 121 publications

(126 citation statements)

References 29 publications

(48 reference statements)

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“…Russell & Bessell ( Regarding the B type stars, Rolleston et al (1993) and Rolleston et al (2002) found, from the analysis of 4 stars in the SMC and 5 stars in the LMC, respectively, mean values of metallicity of −0.8 ± 0.20 dex and −0.31 ± 0.04 dex. Korn et al (2000) In conclusion, the mean iron content of Cepheids, for the Magellanic Clouds, agree very well with the results obtained for non variable stars of similar age and stars that are Cepheid's progenitors.…”

Section: A Comparison With Different Stellar Populations In the Magelmentioning

confidence: 98%

The influence of chemical composition on the properties of Cepheid stars

Romaniello¹,

Primas²,

Mottini³

et al. 2008

A&A

217

266

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Context. The Cepheid period-luminosity (PL) relation is unquestionably one of the most powerful tools at our disposal for determining the extragalactic distance scale. While significant progress has been made in the past few years towards its understanding and characterization both on the observational and theoretical sides, the debate on the influence that chemical composition may have on the PL relation is still unsettled. Aims. With the aim to assess the influence of the stellar iron content on the PL relation in the V and K bands, we have related the V-band and the K-band residuals from the standard PL relations of Freedman et al. (2001, ApJ, 553, 47) and Persson et al. (2004, AJ, 128, 2239, respectively, to [Fe/H]. Methods. We used direct measurements of the iron abundances of 68 Galactic and Magellanic Cepheids from FEROS and UVES high-resolution and high signal-to-noise spectra. Results. We find a mean iron abundance ([Fe/H]) about solar (σ = 0.10) for our Galactic sample (32 stars), ∼−0.33 dex (σ = 0.13) for the Large Magellanic Cloud (LMC) sample (22 stars) and ∼−0.75 dex (σ = 0.08) for the Small Magellanic Cloud (SMC) sample (14 stars). Our abundance measurements of the Magellanic Cepheids double the number of stars studied up to now at high resolution. The metallicity affects the V-band Cepheid PL relation and metal-rich Cepheids appear to be systematically fainter than metal-poor ones. These findings depend neither on the adopted distance scale for Galactic Cepheids nor on the adopted LMC distance modulus. Current data do not allow us to reach a firm conclusion concerning the metallicity dependence of the K-band PL relation. The new Galactic distances indicate a small effect, whereas the old ones support a marginal effect. Conclusions. Recent robust estimates of the LMC distance and current results indicate that the Cepheid PL relation is not Universal.

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Section: A Comparison With Different Stellar Populations In the Magelmentioning

confidence: 98%

The influence of chemical composition on the properties of Cepheid stars

Romaniello¹,

Primas²,

Mottini³

et al. 2008

A&A

217

266

View full text Add to dashboard Cite

show abstract

“…The Galactic photoelectric absorption was set to a column density of N H,GAL = 5.86 × 10 20 cm −2 (Dickey & Lockman 1990) with abundances according to Wilms et al (2000). The additional column density N H,LMC was left as a free parameter with abundances of 0.49 for elements heavier than helium (Rolleston et al 2002). All the uncertainties were calculated based on a Δχ 2 statistic of 2.706, equivalent to a 90% confidence level for one parameter of interest.…”

Section: Spectral Analysismentioning

confidence: 99%

Swift J053041.9-665426, a new Be/X-ray binary pulsar in the Large Magellanic Cloud

Vasilopoulos

Maggi

Haberl

et al. 2013

A&A

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Aims. We observed the newly discovered X-ray source Swift J053041.9-665426 in the X-ray and optical regime to confirm its proposed nature as a high mass X-ray binary. Methods. We obtained XMM-Newton and Swift X-ray data, along with optical observations with the ESO Faint Object Spectrograph, to investigate the spectral and temporal characteristics of Swift J053041.9-665426. Results. The XMM-Newton data show coherent X-ray pulsations with a period of 28.77521(10) s (1σ). The X-ray spectrum can be modelled by an absorbed power law with photon index within the range 0.76 to 0.87. The addition of a black body component increases the quality of the fit but also leads to strong dependences of the photon index, black-body temperature and absorption column density. We identified the only optical counterpart within the error circle of XMM-Newton at an angular distance of ∼0.8 , which is 2MASS J05304215-6654303. We performed optical spectroscopy from which we classify the companion as a B0-1.5Ve star. Conclusions. The X-ray pulsations and long-term variability, as well as the properties of the optical counterpart, confirm that Swift J053041.9-665426 is a new Be/X-ray binary pulsar in the Large Magellanic Cloud.

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“…In particular, the Large Magellanic Cloud (LMC) is actively forming stars in clusters and is an ideal laboratory for us to study star formation, particularly massive star formation in star clusters. In the LMC, the metallicity is a factor of $3 lower than in the solar neighborhood (Dufour et al 1982;Dufour 1984;Rolleston et al 2002). In addition, the visual extinctions are lower and the FUV field is stronger in the LMC than in the Milky Way (Israel et al 1986), characterizing the initial conditions of star formation.…”

Section: Introductionmentioning

confidence: 99%

Submillimeter Observations of Giant Molecular Clouds in the Large Magellanic Cloud: Temperature and Density as Determined fromJ = 3–2 andJ = 1–0 Transitions of CO

Minamidani

Mizuno

et al. 2008

ASTROPHYS J SUPPL S

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We have carried out submillimeter 12 CO(J ¼ 3Y2) observations of six giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC) with the ASTE 10 m submillimeter telescope at a spatial resolution of 5 pc and very high sensitivity. We have identified 32 molecular clumps in the GMCs and revealed significant details of the warm and dense molecular gas with n(H 2 ) $ 10 3 Y10 5 cm À3 and T kin $ 60 K. These data are combined with 12 CO(J ¼ 1Y0) and 13 CO(J ¼ 1Y0) results and compared with LVG calculations. The results indicate that clumps that we detected are distributed continuously from cool ($10Y30 K) to warm (k30Y200 K), and warm clumps are distributed from less dense ($10 3 cm À3 ) to dense ($10 3.5 Y10 5 cm À3 ). We found that the ratio of 12 CO(J ¼ 3Y2) to 12 CO(J ¼ 1Y0) emission is sensitive to and is well correlated with the local H flux. We infer that differences of clump properties represent an evolutionary sequence of GMCs in terms of density increase leading to star formation. Type I and II GMCs (starless GMCs and GMCs with H ii regions only, respectively) are at the young phase of star formation where density does not yet become high enough to show active star formation, and Type III GMCs (GMCs with H ii regions and young star clusters) represent the later phase where the average density is increased and the GMCs are forming massive stars. The high kinetic temperature correlated with H flux suggests that FUV heating is dominant in the molecular gas of the LMC.

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The present-day chemical composition of the LMC

Cited by 121 publications

References 29 publications

The influence of chemical composition on the properties of Cepheid stars

The influence of chemical composition on the properties of Cepheid stars

Swift J053041.9-665426, a new Be/X-ray binary pulsar in the Large Magellanic Cloud

Submillimeter Observations of Giant Molecular Clouds in the Large Magellanic Cloud: Temperature and Density as Determined fromJ = 3–2 andJ = 1–0 Transitions of CO

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